Evaluation of microbiological accumulation capability of the commercial sponge Spongia officinalis var. adriatica (Schmidt) (Porifera, Demospongiae)

This study was carried out to evaluate the microbiological accumulation capability of the demosponge Spongia officinalis var. adriatica. Six microbiological parameters were researched in two sampling periods in the water and in reared sponge samples coming from sites with different degrees of microbial contamination: an off-shore fish farm displaced off the Apulian coast (Southern Adriatic Sea) and a no-impacted area displaced into the Marine Protected Area of Porto Cesareo (Apulian coast-Ionian Sea). We detected the density of culturable heterotrophic bacteria by spread plate on marine agar, total culturable bacteria at 37 degrees C on Plate Count Agar and vibrios on thiosulphate-citrate-bile-sucrose-salt (TCBS) agar. Total and fecal coliforms as well as fecal streptococci concentrations were detected by the MPN method. Bacterial densities were always higher in the sponge homogenates compared with the corresponding seawater in the sampling points and in both sampling periods. As regard vibrios, total culturable bacteria at 37 degrees C and fecal streptococci concentrations, the highest values were observed in the sponge samples coming from the off-shore fish farm during the summer period. The ability of Spongia officinalis var. adriatica to accumulate the microbial pollution indicators suggests that this species can be employed as a bioindicator for monitoring water quality.     

Delayed incubation as an alternative method to sample storage for enumeration of E. coli and culturable bacteria in water

The effects of sample storage on enumeration of Escherichia coli in marine bathing water and culturable bacteria in drinking water were evaluated. Results showed that overnight storage at 0-5 degrees C significantly reduced the counts of E. coli in bathing water (p = 0.0001) with a mean reduction of 25%. A similar effect of sample storage was observed for the enumeration of culturable bacteria in drinking water at 22 +/- 2 degrees C for 66 +/- 4 h (p = 0.0074; mean reduction = 25%) or at 36 +/- 2 degrees C for 44 +/- 4h (p = 0.0353; mean reduction = 6%). The use of a delayed incubation method, i.e. overnight storage at 0-5 degrees C of inoculated agar plates prior to incubation, did not significantly affect the counts of culturable bacteria when plates were incubated at 22 + 2 degrees C for 66 +/- 4 h, whereas it resulted in a significant increase of the bacterial numbers when plates were incubated at 36 +/- 2 degrees C for 44 +/- 4 h (p = 0.0002; mean increase = 32%). Based on these results, it is suggested to avoid the use of overnight or longer sample storage for the enumeration of E. coli in bathing water samples, as well as for the enumeration of culturable bacteria in drinking water. The delayed incubation method appears to be a reliable procedure for the enumeration of culturable bacteria and could represent a valid alternative to sample storage in order to overcome problems associated with the performance of bacteriological counts during weekends or statutory holidays. However, a multi-laboratory study is needed to evaluate the reproducibility of the delayed incubation method for the enumeration of culturable bacteria and its possible use for the enumeration of E. coli by membrane filtration.     

Contribution of drinking water to the weekly intake of heterotrophic bacteria from diet in the United States

The goal of this study was to assess the relative contribution of heterotrophic bacteria from various sources in the normal diet of an average person in the United States, due to concerns regarding the potential health implications of such bacteria in household tapwater. A literature search was conducted to determine the concentration of heterotrophic plate count (HPC) bacteria in drinking water, as well as foods common to the American diet. Food items were also obtained in Tucson, AZ to further evaluate the consumption of HPC and total coliform bacteria. This was compared to a recent study on HPC bacteria in tapwater with and without POU devices mounted on the tap in Tucson, AZ households. It was determined that only 0.048-4.5% of the average consumer's total heterotrophic bacteria intake is derived from drinking water. Thus, HPC bacteria in drinking water do not represent a significant exposure of total HPC bacteria in the average diet of consumers in the United States.     

Influence of Asellus aquaticus on Escherichia coli, Klebsiella pneumoniae, Campylobacter jejuni and naturally occurring heterotrophic bacteria in drinking water

Water lice, Asellus aquaticus (isopoda), frequently occur in drinking water distribution systems where they are a nuisance to consumers and water utilities. Whether they are solely an aesthetic problem or also affect the microbial water quality is a matter of interest. We studied the influence of A. aquaticus on microbial water quality in non-chlorinated drinking water in controlled laboratory experiments. Pure cultures of the indicator organisms Escherichia coli and Klebsiella pneumoniae and the pathogen Campylobacter jejuni as well as naturally occurring heterotrophic drinking water bacteria (measured as heterotrophic plate counts, HPC) were investigated in microcosms at 7 °C, containing non-sterilised drinking water, drinking water sediment and A. aquaticus collected from a non-chlorinated ground water based drinking water supply system. Concentrations of E. coli, K. pneumoniae and C. jejuni decreased over time, following a first order decay with half lives of 5.3, 18.4 and 1.3 days, respectively. A. aquaticus did not affect survival of indicators and pathogens substantially whereas HPC were influenced by presence of dead A. aquaticus. Growth rates increased with an average of 48% for bacteria grown on R-2A agar and an average of 83% for bacteria grown on yeast extract agar when dead A. aquaticus were present compared to no and living A. aquaticus present. A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were measured (up to 25 per living and 500 per dead A. aquaticus) and so were A. aquaticus associated heterotrophic bacteria (>1.8*10⁴ CFU per living and >6*10⁴ CFU per dead A. aquaticus). A. aquaticus did not serve as an optimised habitat that increased survival of indicators and pathogens, since A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were only measured as long as the bacteria were also present in the water and sediment.     

Mytilus galloprovincialis filter feeding on the bacterial community in a Mediterranean coastal area (Northern Ionian Sea, Italy)

This study was carried out seasonally, throughout a year, to evaluate the filtering activity on bacteria of Mytilus galloprovincialis. Six microbiological parameters were researched in the water and mussels samples collected along the coastal area of the Northern Ionian Sea in three stations, S. Vito, Lido Gandoli and Lido Silvana. We detected the densities of culturable heterotrophic bacteria by spread plate on Marine Agar, total culturable bacteria at 37 degrees C on Plate Count Agar and vibrios abundance on thiosulphate-citrate-bile-sucrose-salt (TCBS) agar. Total and fecal coliforms as well as fecal streptococci were determined by the Most Probable Number. Bacterial concentrations at 20 and 37 degrees C as well as vibrios concentrations were higher in the mussel samples compared to the corresponding seawater throughout the year. The results obtained could contribute to improve the information relatively either to the natural processes existing between bacteria and mussels or to the risk of human infections related to the consumption of mussels.     

Use of the membrane filter and a filter aid for concentrating and enumerating indicator bacteria and Salmonella from estuarine waters

A membrane filter -Most Probable Number (MF-MPN) procedure for concentrating and enumerating indicator bacteria and Salmonella from estuarine water is described. In Laboratory studies involving estuarine waters the MF-MPN procedure yielded coliform and fecal coliform recoveries comparable to those obtained by the standard multitube MPN procedure. In a study utilizing a pure culture the MF-MPN procedure yielded Salmonella tennessee recoveries comparable to those obtained by a brain heart infusion pour plate agar method involving 10 replicate plates per dilution.In field studies the MF-MPN method consistently isolated coliform and fecal coliform bacteria from waters which were found to yield indeterminately low values for these two groups of bacteria when examined by the standard multitube MPN method. The MF-MPN method detected Salmonella in three polluted estuarine areas and one unpolluted estuarine area. The described MF-MPN method has the following advantages: (1) bacteria can be concentrated from 4 to 5 l. of water within 5–10 min even when turbidities are as high as 120 Jackson Turbidity Units: (2) several bacterial groups can be determined from the same sample: (3) qualitative and quantitative results can be obtained: (4) small volumes of enrichment broth are required.     

A membrane filter method for the enumeration of aquatic ammonifiers

A standard procedure for the enumeration of heterotrophic bacteria, utilizing heterotrophic plate count medium (m-HPC), has been modified to allow bacterial ammonifier populations also to be counted. Nessler's reagent was included as an outside indicator to ascertain what portion of the population is capable of ammonification. Typically the ammonifier population varied among aquatic habitats, ranging from 0.08 to 37.0% of the heterotrophic population in river water samples, 0.2 to 10.6% for irrigation water samples, and 1.4 to 3.0% for pond and lake water samples.     

Nucleic acid fluorochromes and flow cytometry prove useful in assessing the effect of chlorination on drinking water bacteria

Flow cytometry (FCM), combined with staining using two fluorochromes (propidium iodide, PI, or SYBR Green II RNA gel stain, SYBR-II), was used to assess nucleic acid injuries to chlorinated drinking water bacteria. Highly fluorescent SYBR-II-stained bacteria were converted to bacteria with low fluorescence after chlorination. PI staining of bacteria exposed to different doses of chlorine showed membrane permeabilisation ([Cl2] < 0.2 mg L(-1)) and nucleic acid damage at higher doses ([Cl2] > 0.3 mg L(-1)). Above a threshold dose (between 1.5 and 3 mg Cl2 L(-1)), nucleic acids appeared severely damaged and incapable of being stained by PI or SYBR-II. These results constitute evidence that FCM is a promising tool for assessing drinking water bacteria injuries and for controlling chlorine disinfection efficiency much more rapidly than the standard sensitive but time-consuming heterotrophic plate count method.     

The effect of drinking water treatment on the spatial heterogeneity of micro-organisms: implications for assessment of treatment efficiency and health risk

The effect of drinking water treatment (ferric coagulation, floc blanket clarification, rapid sand filtration) on the spatial heterogeneity of five species of micro-organism was studied at pilot scale. It was found that the spatial heterogeneity of vegetative bacteria (namely total coliform and heterotrophic (22 degrees C; 3 d) bacteria) was little affected by treatment. Indeed, counts of total coliform bacteria within 500 l volumes of treated water were Poisson distributed (i.e. showed minimum variation). In contrast, treatment appeared to increase the spatial heterogeneity (or clustering) of both aerobic spores indigenous to the raw water and Bacillus subtilis var niger spores added to the raw water. Furthermore, B. subtilis var niger spores added to the raw water were detected in the treated water 25 h after termination of spiking to the raw water. The effect on C. parvum oocysts added to the raw water could not be determined because few oocysts broke through treatment into the treated water. Indeed oocyst removals of 5-6 logs were apparent. "Species-specific" differences in the removal ratios were also demonstrated. It is concluded that audits for treatment processes based on single 100 ml "spot" samples for spores will tend to over-estimate the net spore removal and hence underestimate the public health risk. Spatial heterogeneity of counts in treated water contributes to explaining why no "ideal" surrogate has been identified for treatment plant performance.     

Distribution of bacteria in a domestic hot water system in a Danish apartment building

Bacterial growth in hot water systems seems to cause problems such as bad odor of the water, skin allergies and increased heat transfer resistance in heating coils. In order to establish a basis for long-term suppression of bacterial growth, we studied the distribution of bacteria in a Danish domestic hot water system. Heterotrophic plate counts (HPC) were measured in both water and biofilm samples from various sampling sites in the system. In hot water samples, where the temperature was 55-60 degrees C, the HPC were 10(3)-10(4)CFU/mL at incubation temperatures of 25 degrees C or 37 degrees C and 10(5)CFU/mL at 55 degrees C or 65 degrees C. In the cold water (10 degrees C) supplying the hot water system, the HPC at 25 degrees C or 37 degrees C was lower than in the hot water, and no bacteria were found after incubation at 55 degrees C or 65 degrees C. HPC constituted from 38% to 84% of the AODC results in hot water but only 2% in cold water, which showed a high ratio of culturable bacteria in hot water. Biofilm samples from the hot water tank and the inner surface of the pipes in the cold and hot water distribution system were collected by specially designed sampling devices, which were exposed in the system for 42 days. The quasi-steady-state number of bacteria in the biofilm, measured as the geometric mean of the HPC obtained between 21 and 42 days, was five-fold higher in the hot water pipe (13x10(5)CFU/cm(2) at 55 degrees C) than in the cold water pipe (2.8x10(5)CFU/cm(2) at 25 degrees C). There was no significant difference between the number of bacteria in the biofilm samples from the top, middle and bottom of the hot water tank, and the number of bacteria in the biofilm counted at 55 degrees C ranged from 0.6x10(4) to 1.7x10(4)CFU/cm(2). The surfaces of the sacrificial aluminum anodes and the heating coils in the hot water tank also contained high bacterial numbers. The measured number of bacteria in water and biofilm samples was related to the dimensions of the hot water system, and calculations showed that the majority of bacteria (72%) were located in the biofilm especially in the distribution system, which accounts for the greatest surface area. Free-living bacteria accounted for 26% and only a minor part of the bacteria were in the sludge in the hot water tank (2%).     

Pathogenic or potentially pathogenic bacteria as contaminants of fresh water from different sources in Araraquara, Brazil

The microbiological quality of various fresh waters in the Araraquara region, state of São Paulo, Brazil was investigated. Ninety-nine water samples were taken from rivers, reservoirs, artesian and non-artesian wells, springs and tap waters, and these waters were analysed using: plate counts of heterotrophic microorganisms (per 1 ml); Most Probable Number (MPN) of fecal coliforms and E. coli (per 100 ml); tests for presence of Salmonella, Shigella, Yersinia, the E. coli pathogens of classes EPEC, ETEC and EIEC and Mycobacterium, Shigella, Yersinia and enteroinvasive E. coli (EIEC) were not isolated. The other types of microorganisms were isolated in varying proportions. We conclude that the waters investigated represent a potential microbiological health risk.     

The Microbiology of Lubricants and Oils for Water Supply Applications

Recent work in the US has shown that contact between lubricants and oils and drinking water can promote the growth of heterotrophic micro-organisms. It is unlikely that these species are pathogenic, and therefore harmful to man. However, the hygienic status of water distribution systems could be affected, leading to higher heterotrophic plate counts during routine sampling. Experimental work has been undertaken to study the microbiological impact of a range of lubricants and oils on drinking water. The methods have been based on an existing procedure for the assessment of the growth potential of drinking water, i.e. the 'assimilable organic carbon'test. The results of this work could serve as the basis of a future standard method for the rapid and inexpensive screening of oils and lubricants for their microbiological suitability in potable-water applications.     

Isolement de nitrobacter des eaux potables et des eaux urbaines

This study is the first step toward an optimization of the bacterial oxidation of nitrogen compounds in water plants.The goal is to develop a bacterial inoculum, which could be introduced into treatment plants and therefore improve their efficiency for ammonia removal.Nitrobacteria were isolated from sludge and sand used in sewage and drinking water treatment plants. Biomass extraction from inert material was made by means of an Ultrasonic rod. The enrichment in nitrobacteria was made by series of seedings in liquid medium containing only nitrite and mineral salts. Simultaneously the number of heterotrophic bacteria decreased due to the low organic concentration in the medium. When the nitrobacteria population was higher than the heterotrophic one, a drop of the culture was plated on petri-dishes. These dishes used the same mineral medium, added of 60/00 of agar-agar. After 2 weeks of incubation small colonies of nitrobacteria were detected under a stereoscopic magnifying glass. The colonies were collected by a sterile capillary and inoculated in the mineral medium for a check of their ability to oxidize nitrite in nitrate. The purity of the strain was verified with different organic media revealing the presence of heterotrophic contaminants. Pure strains serotypes were characterized with imunofluorescence. All the isolated bacteria were of the same serotype. Nitrobacter winogradskyi serotype agilis.     

Soft deposits, the key site for microbial growth in drinking water distribution networks

In this project we studied the microbiological quality of soft pipeline deposits removed from drinking water distribution networks during mechanical cleaning. Drinking water and deposit samples were collected from 16 drinking water distribution networks located at eight towns in different parts of Finland. Soft pipeline deposits were found to be the key site for microbial growth in the distribution networks. The microbial numbers in the soft deposits were significantly higher than numbers in running water. The highest microbial numbers were detected in the main deposit pushed ahead by the first swab. The deposits contained high numbers of heterotrophic bacteria, actinomycetes and fungi. Also coliform bacteria were often isolated from deposit samples. Manganese and copper in the deposits correlated negatively with the numbers of heterotrophic bacteria. After a year, the viable microbial numbers in the new deposits were almost as high as in the old deposits before the first mechanical cleaning. The bacterial biomass production was higher in the new than in the old deposits.     

Removal of soft deposits from the distribution system improves the drinking water quality

Deterioration in drinking water quality in distribution networks represents a problem in drinking water distribution. These can be an increase in microbial numbers, an elevated concentration of iron or increased turbidity, all of which affect taste, odor and color in the drinking water. We studied if pipe cleaning would improve the drinking water quality in pipelines. Cleaning was arranged by flushing the pipes with compressed air and water. The numbers of bacteria and the concentrations of iron and turbidity in drinking water were highest at 9 p.m., when the water consumption was highest. Soft deposits inside the pipeline were occasionally released to bulk water, increasing the concentrations of iron, bacteria, microbially available organic carbon and phosphorus in drinking water. The cleaning of the pipeline decreased the diurnal variation in drinking water quality. With respect to iron, only short-term positive effects were obtained. However, removing of the nutrient-rich soft deposits did decrease the microbial growth in the distribution system during summer when there were favorable warm temperatures for microbial growth. No Norwalk-like viruses or coliform bacteria were detected in the soft deposits, in contrast to the high numbers of heterotrophic bacteria.     

某市给水管网铁细菌生长特征调查

给水管网中存在的微生物腐蚀现象会造成管网水水质恶化等一系列问题，因此有必要对给水管网中铁细菌的生长特征进行调查研究。选取某市给水管网，分别采用MPN法和平板计数法对管网水及水厂处理单元出水中铁细菌的数量进行测定。试验结果表明：管网水中的铁细菌含量为0～10^7 CFU／mL，变化范围较大，各处理单元出水中均有铁细菌存在；铁细菌数量与管线长度和温度没有相关性，和余氯值呈明显的负相关；铁细菌数量和管网水中总铁以及溶解性铁含量无明显相关性，但和颗粒性铁含量有一定的相关性。     

Enumeration of salmonellae in wastewater by the MPN technique

A comparative study of the use of double and single strength RV enrichment media for the enumeration of salmonellae by the MPN method was carried out. Of 53 samples of raw municipal wastewater and waste stabilization pond effluents examined 83% yielded higher numbers of positive tubes when the various volumes of the samples utilized for the estimations were inoculated into single strength RV enrichment medium than when inoculated into double strength medium. Extending the incubation period of the XLD agar plates from 24h to 48h at 37°C increased the number of confirmed positive tubes by 1–9% with a mean value of 3%. The effect of the strength of the enrichment medium used on the MPN values is discussed.     

Relationship between coliform culturability and organic matter in low nutritive waters

The objective of this work was to investigate the behaviour of coliform bacteria in specific low nutritive waters conveying organic fractions from different origin of which an unknown part is likely to pass through the treatment barrier. For this purpose, we studied the growth (microscopic counting) and the culturability (count on nutritive medium) of ten coliform bacteria species as a function of the amount of organic matter in a river water collected after a period of heavy rain and in an algal bloom water. Assays were carried out in the presence of autochthonous heterotrophic bacteria from the Nancy (France) drinking water, with variable concentrations of dissolved organic carbon (DOC) representative of drinking waters (0.5-1.5 mg l(-1) for diluted river water samples and 1.3-2.5 mg l(-1) for diluted algal bloom water samples). Bacterial growth was measured in the two types of water, regardless of the initial concentration of DOC. We found that coliform bacteria lost their culturability in both sample series, and that the lower the initial DOC concentration the more rapidly the culturability was lost. The quantity of DOC consumed by the bacteria in the two water types (0.03-0.13 mg l(-1) in river water and 0.77-1.29 mg l(-1) in algal bloom water) and the resulting consequences on bacterial behaviour suggested that bloom water contains algal organic compounds that are antagonistic to the growth and/or the culturability of coliform bacteria. Organic matter thresholds, beyond which coliform bacteria are unlikely to keep their culturability, have not been determined experimentally. Indeed, at the end of the assays some culturable coliform bacteria were systematically detected in both types of water. Enterobacter cloacae was the predominant species. Thus, during these adverse events the probability of coliform occurrence can be considered as high in treated water.     

Rapid, cultivation-independent assessment of microbial viability in drinking water

Fast and accurate monitoring of chemical and microbiological parameters in drinking water is essential to safeguard the consumer and to improve the understanding of treatment and distribution systems. However, most water utilities and drinking water guidelines still rely solely on time-requiring heterotrophic plate counts (HPC) and plating for faecal indicator bacteria as regular microbiological control parameters. The recent development of relative simple bench-top flow cytometers has made rapid and quantitative analysis of cultivation-independent microbial parameters more feasible than ever before. Here we present a study using a combination of cultivation-independent methods including fluorescence staining (for membrane integrity, membrane potential and esterase activity) combined with flow cytometry and total adenosine tri-phosphate (ATP) measurements, to assess microbial viability in drinking water. We have applied the methods to different drinking water samples including non-chlorinated household tap water, untreated natural spring water, and commercially available bottled water. We conclude that the esterase-positive cell fraction, the total ATP values and the high nucleic acid (HNA) bacterial fraction (from SYBR((R)) Green I staining) were most representative of the active/viable population in all of the water samples. These rapid methods present an alternative way to assess the general microbial quality of drinking water as well as specific events that can occur during treatment and distribution, with equal application possibilities in research and routine analysis.     

Drinking water quality in the Ethiopian section of the East African Rift Valley I--data and health aspects

Drinking water samples were collected throughout the Ethiopian part of the Rift Valley, separated into water drawn from deep wells (deeper than 60 m), shallow wells (<60 m deep), hot springs (T>36 degrees C), springs (T<32 degrees C) and rivers. A total of 138 samples were analysed for 70 parameters (Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Ga, Gd, Ge, Hf, Hg, Ho, I, In, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, NO(2), NO(3), Pb, Pr, Rb, Sb, Se, Si, Sm, Sn, SO(4), Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr, temperature, pH, conductivity and alkalinity) with ion chromatography (anions), spectrometry (ICP-OES and ICP-MS, cations) and parameter-specific (e.g. titration) techniques. In terms of European water directives and WHO guidelines, 86% of all wells yield water that fails to pass the quality standards set for drinking water. The most problematic element is fluoride (F), for which 33% of all samples returned values above 1.5 mg/l and up to 11.6 mg/l. The incidence of dental and skeletal fluorosis is well documented in the Rift Valley. Another problematic element may be uranium (U)-47% of all wells yield water with concentrations above the newly suggested WHO maximum acceptable concentration (MAC) of 2 microg/l. Fortunately, only 7% of the collected samples are above the 10 microg/l EU-MAC for As in drinking water.